Top-opening carton



April 21, 1970 R. o. STUBERG TOP-OPENING CARTON Filed March 28, 1968 FlG1 INVENTOR. ROBERT O. STUBERG BY 7mm FlG 4 ATTORNEYS United StatesPatent 3,507,440 TOP-OPENING CARTON Robert O. Stuberg, 101 Bella VistaDrive, Hillsborough, Calif. 94010 Filed Mar. 28, 1968, Ser. No. 716,755Int. Cl. B65d /02, 5

US. Cl. 229-33 5 Claims ABSTRACT OF THE DISCLOSURE A top-opening cartonfor minimizing moisture/vapor loss from frozen comestibles within thecarton through the use of a front flap corresponding in shape to acutaway segment of the respective wall panel. When the flap is tuckedinside this cutaway segment of the wall panel and pressure employed toaccomplish sealing (either by gluing or by softening a thermoplasticcoating), the resiliency of the paperboard proximate the score line ofthe flap and the back-up support created by the top panel provideresistance in opposition to the applied pressure so that a continuousseal is formed across the front of the carton, using a minimum or muchsmaller blank than normally required.

This invention is directed to a top-opening carton. More particularly,the invention is directed to a topopening carton suitable for minimizingmoisture and vapor loss during storage of packaged products.

Present commercially available top-opening (topclosing) carton-s utilizea lid hingedly secured along one edge thereof to one side wall panel ofa rectangularlyshaped body. Flaps extend outwardly from the other threeedges of the lid to provide an overlap with the respective wall panelsof the body. In operation the body is filled with the particularmaterial being packaged and the lid positioned to cover the bodyopening. Then the overlapping flaps are adhered (or locked by means ofmale and female locking cuts and tabs) to respective wall panels toretain the lid member as a closure for the opening in the body. Themethod for adhering the flaps to the Walls of the body conventionallyinvolves, for example, applying glue and pressure for attachment or bylocking of the flaps to the outside of the wall panels. Alternately,where the carton blank is formed with a thermoplastic surface coating,appropriate portions of the coating are first softened and thereafterthe flaps are maintained in contiguous association with respective ofthe wall panels of the body while the tacky thermoplastic coating isallowed to cool and solidify. The adherence is normally accomplishedalong the lower portion of the respective wall panel where the bottompanel provides the necessary back-up pressure. In this manner, the flapsare secured to the body, thereby providing an integral enclosure, untilthe carton contents are to be utilized.

Although this type of carton is quite satisfactory when it is employedin conjunction with a tightly-sealed moisture/vapor impervious overwrapor when the comestible is initially packaged in a heat-sealed plasticbag and the bag inserted in the carton, this conventional carton in andof itself does not provide the degree of moisture/ vapor retentionnecessary to prevent product degradation or even minimize the ratethereof irrespective of the adhering technique employed. Theoppositely-disposed flaps can be subjected to sufficient pressure duringthe adhering procedure to provide a bond exhibiting satisfactorymoisture/vapor characteristics, but the flap overlapping the front wallpanel cannot be sealed as effectively. Further-more, as the frontoverfiap is reduced in width, less resistance is provided by the frontpanel. Al-

3,507,440 Patented Apr. 21, 1970 through the front panel may be rigidalong the score lines forming its side edges and lower edge (where backpressure is provided by the adjoining perpendicular panel), the internalarea of the wall panel is quite flexible. Thus, the upper portionthereof provides insufiicient resistance or back pressure in oppositionto the force applied for accomplishing physical contact between theoverlapping flap and the front wall panel. As a result, the desiredadherence is not obtained. In other words, with present cartonstructures, sufficient pressure cannot be applied along the overlapfront flap and against the whole front wall panel to create uniformcontact and adherence. Thus, the continuity of seal necessary to form anadequate moisture/vapor barrier along the front of the carton is notprovided.

It is the principal object of this invention to provide a carton closurethat produces a good bond using glue or thermoplastic coatings.

It is a further object of this invention to eliminate the need for amoisture/vapor impervious overwrap or an inner heat-sealed plastic bag(innerwrap) in frozen food consumer packages.

It is another object of this invention to provide an open-topped cartonthat can be effectively sealed at speeds currently employed inassembling lock or glue style closures.

It is still another object of this invention to provide an open-toppedfrozen food carton that can be conveniently heat sealed.

It is a further object of this invention to provide a top-opening frozenfood carton from a single sheet blank. t

It is a feature and advantage of this invention to utilize a flap thattucks within the upper portion of the frontal wall panel of top-openingcarton so that when pressure is applied against the upper portion of thefrontal wall panel, the pressure will be resisted by both the naturalresiliency of the flap to-spring back about the score line between theflap and the lid, and the edge rigidity of the top panel.

These objects, features and advantages will be better understood andothers will become apparent when reference is made to the followingdetailed disclosure especially in view of the attached drawing wherein:

FIG. 1 is a perspective view of a carton blank showing one embodimentincorporating the features of this invention; and

FIGS. 2, 3 and 4 are partially cutaway perspective views illsutratingthe sequential steps involved in obtaining the finished carton of thisinvention from the embodiment of FIG. 1.

Referring more particularly to the drawing, wherein similar charactersof reference represent corresponding parts in each of the several views,in FIG. 1 there is shown a carton blank A that has been formed from aflat sheet of flexible material in a conventional manner such as withrotary blank-forming (or die-cut forming) paperboard manufacturingequipment.

Blank A includes a number of longitudinal score lines 10 and a number oftransverse score lines 12 disposed to form bottom panel 14, top panel 16and side panels 18, 20, 22 and 24. Flaps 26, 28 and 30 are hingedlyattached to top panel 16 along respective of score lines 10 and 12. Sidepanels 18 and 22 are also provided with flaps 32, 32', 32" and 32",extending from respective of their edges for attachment to respectiveportions of side panels 20 and 24, such as by gluing, to form arectangular body from blank A. It will be apparent to one skilled in theart that gluing is merely one of a number of methods of interconnectingthe various side walls to provide a rectangular body for the carton. Thebody of the carton may also be formed by interlocking tongues and slitsas well as by heat sealing the flaps to the side panels.

Turning more specifically to side panel 22, it includes a score line 36intermediate the height of panel 22 and extending for a substantial partof the length thereof. Slits 38 and 38 extend from respective ends ofscore line 36 out to the outer edge of panel 22. Slits 38 and 38', scoreline 36, and the outer elongated edge of side panel 22 define an uppersegment (portion) 40. Extension 28 is formed with an outer edge 42 andside edges 44 and 44 to provide a flap corresponding in configuration toupper segment 40 of panel 22. In this manner, after extension 28 isinserted within the body of the carton formed by blank A, upper segment40 can be bent away for inserting glue or for heating a thermoplasticcoating on the outer surface of extension 28 and the inner surface ofsegment 40. In another aspect, it is advantageous for both flap 28 andupper segment 40 to be of trapezoidal configuration so that segment 40can also be moved out of the plane of side panel 22, if desired, toallow for insertion of flap 28 within the body of the carton.

Referring now to FIGS. 2-4 depicting the assemblage of carton B, bodyportion including bottom panel 14 and side wall panels 18, 20, 22 and 24are assembled in a conventional manner. Thereafter, fiaps 26 and 30 aresecured to respective of side walls 24 and 20. Upper portion 40 is thenmoved out of the plane of wall panel 22 to provide a path of ingress forflap 28 as shown most clearly in FIG. 2. Referring to FIG. 3, fiap 28 isinserted entirely within the plane of panel 22. Upper segment 40 is thenattached to panel 28 to provide the final structure as shown in FIG. 4.A heated die is inserted between the inner surface of upper segment 40and the outer sur face of flap 28 to elevate the temperature of thethermoplastic coating so that it will become tacky. Thereafter, pressureis applied against the outside surface of upper segment 40 so that theinside thereof is forced into intimate contact with the outer surface offlap 28. Flap 28, because of the resiliency of the flexible materialcomprising blank A, tends to spring outwardly around score line 12towards its original fiat position. In this manner, flap 28 will pushback against the force being applied to upper portion 40 and provide thecontinuity of contact required to obtain an adequate seal. It will beapparent to one skilled in this art that as the width of flap 28increases, the resiliency of the flap will diminish. Thus, it ispreferable to form flap 28 with as small a width as possible. In thismanner, optimum advantage is also obtained from back-up support providedby top panel 16. In this regard, it has been found most advantageous toutilize a flap 28 having a Width no greater than half the height ofpanel 22 and preferably of from about /2 inch to /8 inch wide.

In a preferred embodiment, and as shown most clearly in FIG. 3, it isdesirable that flap 28 have a slightly larger cross-sectional area thanupper portion 40. In this manner, when segment 40 is sealed against fiap28, the surface of flap 28 will overlap slits 38 and 38 and ensure amore effective moisture-vapor barrier.

The thermoplastic surface coating employed in this in vention can be anyof those presently commercially available to the packaging industryincluding polymers of polyethylene and the like. Such coating materialsare suitable for direct on-carton printing and are especiallyadvantageous in this invention where the need for a printed overwrap isdiminished.

Although the foregoing invention has been described in some detail byway of illustration for purposes of clarity of understanding, it will beapparent to one skilled in this art that certain changes andmodifications may be practiced within the spirit of this invention.

What is claimed is:

1. A top-closing carton comprising: an open-topped body having a heightdefined by four interconnected side walls; a lid having a first edgethereof hingedly secured to the upper edge of one of said sidewalls andmovable into covering relationship with the open top of said body, saidlid including a pair of flaps hingedly secured to second and third edgesthereof, a sidewall other than said one side wall having a score lineextending along a portion of its length intermediate its height, saidother sidewall being further provided with a pair of slits extendinginwardly from the upper corners thereof to respective ends of said scoreline, to define a trapezoidal segment with the upper portion of saidother sidewall; said lid having a trapezoidal-shaped extension hingedlysecured along a score line to the fourth edge of said lid, saidextension defining a width greater than the height of said trapezoidalsegment and being movable into said body; and means for adhering theoutside of said extension to the inside of said segment; whereby whensaid extension is adhered to said segment, said extension will coversaid slits to minimize moisture-vapor loss from within said carton.

2. A top-opening carton in accordance with claim l and furthercharacterized by means for adhering the inside of said pair of flaps tothe outside of respective of said side walls.

3. A top-opening carton in accordance with claim 2 wherein said adheringmeans is by a thermoplastic coating that becomes tacky when subjected tosufficient heat.

4. A blank for forming a top-closing carton suitable for minimizingmoisture-vapor loss from within said carton, comprising: a substantiallyflat, vapor-impervious sheet cut and scored to provide a series of wallpanels hingedly connected to a bottom panel and adapted to beinterconnected to each other, one of said wall panels also beinghingedly connected to one edge of top panel corresponding inconfiguration to said bottom panel; a wall panel other than the wallpanel hingedly connected to the top panel including a moisture-vaporimpervious score line along a portion of its length to define a lineintermediate to its Width, said other Wall panel being further providedwith a pair of slits extending inwardly from the upper corners thereofto respective ends of said score line, to define a trapezoidal segmentwithin the upper portion of said wall panel; flaps hingedly attached toeach of the other three edges of said top panel, two of said fiaps beingof a size sufficient to overlap respective of said wall panels, theremaining flap being of a trapezoidal cross-section for overlaying saidother wall panel, said remaining flap defining a width greater than theheight of said trapezoidal segment and being movable into said body soas to abut said segment; and means for adhering opposite of said twoflaps to the outside of respective of said wall panels and saidremaining flap to the inside of said opposite wall panel at saidtrapezoidal segment.

5. A blank in accordance with claim 4 wherein said adhering meanscomprises a thermoplastic coating.

References Cited UNITED STATES PATENTS 1,992,222 2/1935 La Grua 2295l2,038,893 4/1936 Davidson 22951 2,104,195 1/1938 Groeling 229-332,122,885 7/1938 Lowey 229-5l X 2,828,060 3/1958 Brown 229-51 X3,306,517 2/ 1967 Diesinger 2 2 9-37 DAVIS T. MOORHEAD, Primary ExaminerU.S. Cl. X.R. 22937, 51

